Look at the row labeled Cat. How many students chose cat as their favorite pet?

Probability of an event is $\dfrac{\text{number of favorable outcomes}}{\text{total number of outcomes}}$. Write that fraction for this situation, then convert your fraction to a decimal to match the answer choices.

In Desmos, type 9/30 and look at the decimal value it gives. Then match that decimal to one of the answer choices.

From the table, add all the students to confirm the total:

So there are $30$ students in total, which matches what the problem says.

We want the probability that a student chose cat as their favorite pet.

From the table, the number of students who chose cat is $9$.

Probability is

Now simplify this fraction by dividing numerator and denominator by $3$:

The fraction $\frac{3}{10}$ is equal to $0.3$, which can be written as $0.30$.

So the probability that a randomly chosen student picked cat is $0.30$, which corresponds to answer choice B) 0.30.